The present invention relates to a resonator arrangement for electron spin resonance spectroscopy having an upper carrier plate, a long center portion and a long resonator section.
Resonator arrangements of the before-described type have been known before.
In electron spin resonance spectroscopy, an electromagnetic microwave field is excited in a resonator in order to enable a sample under examination to be exposed to a magnetic microwave field of predetermined direction. The resonator is positioned for this purpose in a constant magnetic field of high homogeneity and intensity, whose field lines extend perpendicularly to the direction of the magnetic microwave field.
Due to the necessary homogeneity of the constant magnetic field, the resonator usually is positioned in a narrow air gap between pole shoes of a laboratory magnet. This means that the space available is very limited. Usual resonator arrangements for electron spin resonance spectroscopy, therefore, consist of the very narrow lower resonator portion, which contains the resonant structure proper (cavity resonator, helix resonator, band resonator) with the sample, a long center portion serving essentially for transferring the microwave signal, and finally an upper carrier section on which the necessary connections are provided.
These connections comprise firstly the connection for the microwave signal, i.e. for example the flange of a hollow waveguide, or a plug-in connection for a microwave coaxial line. The connections further comprise mechanical mounting means, connections for supplying a modulation signal, for carrying off measured voltages, for example of a thermoelement, and connections for supplying or carrying off liquid or gaseous temperature-control agents. Depending on the complexity of the experiment to be carried out, there may also be provided holding means for goniometers in order to enable isotropy measurements to be carried out, further connections for irradiating or passing through optical or other radiation, and the like more. Finally, there have also been known resonator arrangements where the carrier plate comprises an additional feeding arrangement by means of which the sample can be introduced into the resonator section.
For the reasons set out above it is clear that the carrier section or the carrier plate must be given a relatively big size if all the functions enumerated above are to be implemented.
In the case of conventional resonator arrangements, one always designs the particular arrangement for a given experiment, and there is no or hardly any possibility to vary the measuring conditions for one and the same resonator arrangement. This is true in particular if different measuring frequencies of a microwave signal are to be employed, or if temperatures in the area of the measuring sample or different types of resonator arrangements are to be used, for example for continuous-wave measurements on the one hand and pulsed measurements on the other hand, or for measurements with or without irradiation.
With conventional resonator arrangements it is therefore necessary to exchange substantially the whole arrangement if different experiments are to be carried out.